From a6cd5f44dbd25e8420d3f0643a2b3bbd607d99bb Mon Sep 17 00:00:00 2001
From: Jeffrey Pfau <jeffrey@endrift.com>
Date: Sun, 30 Oct 2016 02:52:20 -0700
Subject: [PATCH] GBA Memory: Fix VCOUNT being writable

---
 CHANGES      | 1 +
 src/gba/io.c | 6 +++++-
 2 files changed, 6 insertions(+), 1 deletion(-)

diff --git a/CHANGES b/CHANGES
index 733a8c2bb..13ce295fa 100644
--- a/CHANGES
+++ b/CHANGES
@@ -21,6 +21,7 @@ Bugfixes:
  - VFS: Fix resizing memory chunks when not needed
  - GB Memory: Fix patching ROM bank 0
  - GB: Fix audio not being deinitialized
+ - GBA Memory: Fix VCOUNT being writable
 Misc:
  - SDL: Remove scancode key input
  - GBA Video: Clean up unused timers
diff --git a/src/gba/io.c b/src/gba/io.c
index 8eb2c4926..63c9dca6e 100644
--- a/src/gba/io.c
+++ b/src/gba/io.c
@@ -336,7 +336,7 @@ void GBAIOInit(struct GBA* gba) {
 }
 
 void GBAIOWrite(struct GBA* gba, uint32_t address, uint16_t value) {
-	if (address < REG_SOUND1CNT_LO && address != REG_DISPSTAT) {
+	if (address < REG_SOUND1CNT_LO && (address > REG_VCOUNT || address == REG_DISPCNT)) {
 		value = gba->video.renderer->writeVideoRegister(gba->video.renderer, address, value);
 	} else {
 		switch (address) {
@@ -346,6 +346,10 @@ void GBAIOWrite(struct GBA* gba, uint32_t address, uint16_t value) {
 			GBAVideoWriteDISPSTAT(&gba->video, value);
 			return;
 
+		case REG_VCOUNT:
+			mLOG(GBA_IO, GAME_ERROR, "Write to read-only I/O register: %03X", address);
+			return;
+
 		// Audio
 		case REG_SOUND1CNT_LO:
 			GBAAudioWriteSOUND1CNT_LO(&gba->audio, value);